Adjustable dumbbell

ABSTRACT

The present invention relates to an adjustable dumbbell, which includes a dumbbell body and dumbbell pieces cumulatively attached to both ends of the dumbbell body, wherein the dumbbell body includes a grip rod and mounting portions, further includes a first telescopic rod and a second telescopic rod, the number of dumbbell pieces hanging on the first telescopic rod and the second telescopic rod is controlled by the first telescopic rod and the second telescopic rod extending from or retracting into both ends of the dumbbell body in opposite directions, thereby adjusting the weight of dumbbells. The first telescopic rod and the second telescopic rod are disposed in a semicircular shaft shape, and the first telescopic rod and the second telescopic rod are staggered, so that the lengths of the first telescopic rod and the second telescopic rod are doubled, and the number of adjustable dumbbell pieces is greatly increased.

This application claims priority to Chinese Patent Application 202011509895.3, filed on Dec. 18, 2020, which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the field of fitness equipment, in particular to a dumbbell of which the number of dumbbell pieces is adjustable, specifically to the improvement of a telescopic rod structure therein.

BACKGROUND

Dumbbell is a kind of commonly used fitness equipment. The existing adjustable dumbbell, such as the patent whose publication number is CN111450475, proposes that two retractable telescopic shafts are disposed and extending inside the dumbbell handle, and the number of dumbbell pieces hanging on the telescopic shafts is controlled by the telescopic shafts extending from or retracting into both ends of the dumbbell handle in opposite directions, thereby adjusting the weight of dumbbells. In this structure, the telescopic shaft used is a circular shaft structure, and the telescopic shaft extends through a center hole provided in the dumbbell handle; it has a disadvantage that the length of the dumbbell handle is limited. For example, two circular shaft-type telescopic shafts are disposed and extending inside the dumbbell handle, the length of each telescopic shaft is only half of the length of the dumbbell handle at most, and the length of the telescopic shaft is limited, so the number of dumbbell pieces that can be adjusted by the telescopic shaft is greatly limited.

SUMMARY

Therefore, in view of the above problems, the present invention provides an adjustable dumbbell with an optimized structure.

The present invention is realized by employing the following technical solutions:

the present invention provides an adjustable dumbbell, comprising a dumbbell body and dumbbell pieces cumulatively attached to both ends of the dumbbell body, wherein the dumbbell body includes a grip rod and mounting portions disposed at both ends of the grip rod for connecting the dumbbell pieces, the dumbbell body further includes a first telescopic rod and a second telescopic rod, which extend inside the dumbbell body, the first telescopic rod and the second telescopic rod are driven by the dumbbell body to extend from or retract into the dumbbell body away from each other to hang the dumbbell piece, thereby adjusting the number of dumbbell pieces at both ends of the dumbbell body, the first telescopic rod and the second telescopic rod are substantially semicircular shaft shaped, the first telescopic rod includes a first semicircular plane and a first diametral plane that enclose a semicircular shaft shape, the first diametral plane is provided with a first sliding groove opened in a length direction of the first telescopic rod thereon, the second telescopic rod includes a second semicircular plane and a second diametral plane that enclose a semicircular shaft shape, the second diametral plane is provided with a second sliding groove opened in a length direction of the second telescopic rod, a plane where the first diametral plane is located and a plane where the second diametral plane is located face each other, so that the first telescopic rod and the second telescopic rod are staggeredly arranged in the dumbbell body, the dumbbell body is fixedly provided with a first limiting block and a second limiting block respectively matching the first sliding groove and the second sliding groove, which are respectively slidably engaged in the first sliding groove and the second sliding groove, thereby restricting a circumferential rotation of the first telescopic rod and the second telescopic rod.

Wherein, based on assembly and manufacturing considerations, it is preferable that both ends of the dumbbell body have a first exposing hole and a second exposing hole for exposing the first telescopic rod and the second telescopic rod, which are respectively semicircular shapes matching the shapes of the first telescopic rod and the second telescopic rod, the first limiting block and the second limiting block are respectively fixedly disposed in the first exposing hole and the second exposing hole.

Wherein, in order to improve the stability of the first telescopic rod and the second telescopic rod and their assembly, it is preferable that the first telescopic rod further includes a first sliding block disposed on the first diametral plane, and the second telescopic rod further includes a second sliding block disposed on the second diametral plane, the first sliding block is slidably connected in the second sliding groove, while the second sliding block is slidably connected in the first sliding groove, so that the first telescopic rod and the second telescopic rod are slidably connected.

Wherein, in order to improve the safety performance, it is preferable that the first sliding groove has a first end, the second sliding groove has a second end, when the first telescopic rod and the second telescopic rod are extended away from each other, the first sliding block and the second sliding block is able to abut against the second end and the first end, respectively, thereby restricting the first telescopic rod and the second telescopic rod to disengage from each other.

Wherein, in order to improve the safety performance, it is preferable that an end of the first telescopic rod and the second telescopic rod pointing to an outside of the dumbbell body has a hooking portion extending radially, when the first telescopic rod and the second telescopic rod are retracted, the hooking portion is able to be hooked on end faces of both ends of the dumbbell body, thereby restricting the first telescopic rod and the second telescopic rod to retract into the dumbbell body.

Wherein, in order to improve the overall aesthetics of the telescopic rod, it is preferable that the hooking portion complements the end of the first telescopic rod and the second telescopic rod pointing to the outside of the dumbbell body into a circular shape.

Wherein, in order to improve the accuracy of a telescopic movement of the telescopic rods, it is preferable that the first telescopic rod and the second telescopic rod are connected to the dumbbell body by a screw pair with opposite rotation directions, so that by rotating the dumbbell body, the first telescopic rod and the second telescopic rod are driven to extend from or retract into the dumbbell body away from each other.

Wherein, based on manufacturing and cost considerations, it is preferable that the first semicircular plane and the second semicircular plane are protrudingly provided with a first thread and a second thread with opposite rotation directions, respectively, and the dumbbell body is provided with a first helical groove and a second helical groove that are matingly connected with the first thread and the second thread, respectively.

Preferably, the end of the first telescopic rod and the second telescopic rod pointing to the outside of the dumbbell body has a diameter enlarged portion with an enlarged diameter.

Wherein, in order to ensure the stable support of the telescopic rod to the dumbbell piece, it is preferable that the dumbbell pieces are provided with 180° symmetrically disposed clamping blocks and clamping grooves, adjacent dumbbell pieces are cumulatively stacked at both ends of the dumbbell body through snap fitting of the clamping blocks and clamping grooves between them, and a connecting line of centers of each group of the 180° symmetrically disposed clamping blocks and clamping grooves is in the plane where the first diametral plane or the second diametral plane is located.

The present invention has the following beneficial effects: in the present invention, the first telescopic rod and the second telescopic rod are configured in a semicircular shaft shape and are staggeredly arranged, so that the lengths of the first telescopic rod and the second telescopic rod are doubled, and the number of adjustable dumbbell pieces is greatly increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an adjustable dumbbell in an embodiment;

FIG. 2 is a schematic view of a first dumbbell piece at both ends of a dumbbell body being fixedly connected with the dumbbell body in an embodiment;

FIG. 3 is a schematic view of the dumbbell piece in an embodiment;

FIG. 4 is a schematic view of the dumbbell body in an embodiment;

FIG. 5 is a cross-sectional view of the dumbbell body in an embodiment;

FIG. 6 is an exploded view of the dumbbell body in an embodiment;

FIG. 7 is a schematic diagram of a telescopic rod assembly in an embodiment;

FIG. 8 is a schematic view of a second telescopic rod in an embodiment;

FIG. 9 is a cross-sectional view of the telescopic rod assembly in an embodiment;

FIG. 10 is a schematic view of a dumbbell piece mounting plate mounted at one end of the dumbbell body in an embodiment;

FIG. 11 is a schematic view of a second telescopic rod and the dumbbell piece in an embodiment;

FIG. 12 is a schematic view of a fixed assembly of a grip rod and a flange driving member in an embodiment;

FIG. 13 is a schematic view (first angle) of the flange driving member in an embodiment;

FIG. 14 is a schematic view (second angle) of the flange driving member in an embodiment;

FIG. 15 is a schematic view of a planetary gear system in an embodiment;

FIG. 16 is an exploded view of the planetary gear system in an embodiment; and

FIG. 17 is a schematic sectional view of a gear shaft in the embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To further illustrate respective embodiment, the present invention is provided with the accompanying drawings. The drawings are a part of the disclosure of the present invention, which are mainly used to illustrate embodiments, and can be taken in conjunction with the relative depiction in the description to explain the operation principle of the embodiments. With reference to these contents, other possible embodiments and the advantages of the present invention will be understood by those skilled in the art. The components in the drawings are not drawn to scale, and similar component signs are usually used to represent similar components.

The present invention will be further explained in conjunction with the drawings and the specific embodiments.

Referring to FIGS. 1-2, as a preferred embodiment of the present invention, an adjustable dumbbell is provided, which includes the dumbbell body 10 having a substantially “I” shape and a plurality of dumbbell pieces 20 mounted and disposed at both ends of the dumbbell body 10, the first dumbbell pieces 20 at both ends of the dumbbell body 10 are fixedly connected with the dumbbell body 10, the remaining dumbbell pieces 20 are cumulatively mounted on the first dumbbell pieces 20 at both ends of the dumbbell body 10. As shown in FIG. 3, left and right end faces of each dumbbell piece are symmetrically provided with a dovetail tenon and a dovetail groove at 180°, and an accumulation of dumbbell pieces is realized by the mating connection of the dovetail tenon and the dovetail groove on adjacent dumbbell pieces.

Referring to FIGS. 4-6, the dumbbell body 10 includes a grip rod 1, a flange driving members 2 fixedly disposed at both ends of the grip rod 1, a planetary gear system 4 in driven connection with the flange driving member 2, and a telescopic rod assembly 6 extending inside the dumbbell body 10. The flange driving member 2 is butted with the planetary gear system 4 so as to serve as a mounting part for connecting both ends of the dumbbell body 10 with the dumbbell piece. The telescopic rod assembly 6 includes a first telescopic rod 61 and a second telescopic rod 62 having a substantially semicircular shaft shape. By rotating the grip rod 1 and via the transmission of the flange driving member 2 and the planetary gear system 4, the dumbbell body 10 finally makes the first telescopic rod 61 and the second telescopic rod 62 to extend or retract synchronously and away from each other. The first telescopic rod 61 and the second telescopic rod 62 hang the dumbbell pieces through center holes of the dumbbell pieces, so as to adjust the number of dumbbell pieces at both ends of the dumbbell body 10. Specifically, as shown in FIGS. 7-9, the telescopic rod assembly 6 includes two similarly structured, substantially semicircular shaft-shaped first telescopic rod 61 and second telescopic rod 62. The first telescopic rod 61 and the second telescopic rod 62 are staggeredly arranged and slidably connected. Taking the second telescopic rod 62 as an example, the second telescopic rod 62 includes a second semicircular plane 620 and a second diametral plane 621 that enclose a semicircular shaft shape, the second semicircular plane 620 is provided with a convex second thread 622, the second thread 622 is able to engage with a helical groove 462 of the gear shaft 46 on the planetary gear system 4, to realize the helical transmission between the second telescopic rod 62 and the dumbbell body 10. The second diametral plane 621 has a second sliding groove 624 opened in a length direction of the second telescopic rod 62, the second sliding groove 624 has a second end 6241. The second diametral plane 621 is provided with a convex second sliding block 625 with a shape matching the second sliding groove 624. At one end of the second telescopic rod 62 pointing to the outside of the dumbbell body 10 is provided with a second hooking portion 623 in a semicircular shape extending in the radial direction of the second telescopic rod 62. The second hooking portion 623 complements the end of the second telescopic rod 62 pointing to the outside of the dumbbell body 10 into a circular shape matching the center hole of the dumbbell piece to improve the overall aesthetics of the telescopic rod. As shown in FIG. 5, the second hooking portion 623 exposes out of the dumbbell body 10. When the second telescopic rod 62 is retracted into the dumbbell body 10, the second hooking portion 623 is able to be hooked on an end face of the dumbbell body 10, thereby restricting the second telescopic rod 62 to retract into the dumbbell body 10, to prevent the dumbbell piece from falling off the second telescopic rod 62. The first telescopic rod 61 is similar in structure to the second telescopic rod 62, it has a first semicircular plane, a first diametral plane, a first sliding groove, a first end, a first sliding block, and a first hooking portion having the same structures as the second semicircular plane 620, the second diametral plane 621, the second sliding groove 624, the second end 6241, the second sliding block 625, and the second hooking portion 623 as described above. The only difference between the first telescopic rod 61 and the second telescopic rod 62 is that the rotating directions of the threads (such as the second threads 622) on the first telescopic rod 61 and the second telescopic rod 62 are opposite, so that when the grip rod 1 is rotated, the first telescopic rod 61 and the second telescopic rod 62 are able to extend or retract in opposite directions.

When the first telescopic rod 61 and the second telescopic rod 62 are assembled, the first diametral plane and second diametral plane 621 are disposed substantially face-to-face, the second sliding block 625 is inserted into the first sliding groove, and the first sliding block is inserted into the second sliding groove 624, so that the first telescopic rod 61 and the second telescopic rod 62 are slidably connected together, to further limit play of the first telescopic rod 61 and the second telescopic rod 62 by a guiding effect of the sliding groove, and improve the stability of movement and assembly of the first telescopic rod 61 and the second telescopic rod 62. When the first telescopic rod 61 and the second telescopic rod 62 extend away from each other, the second end 6241 of the second sliding groove 624 and the first end of the first sliding groove form limit stops for the first sliding block and the second sliding block 625, respectively, thereby realizing the limit in extension directions of the first telescopic rod 61 and the second telescopic rod 62, and preventing the disengagement of the two from causing potential safety hazards. The first and second sliding grooves 624 also serve to form a circumferential limit to the first telescopic rod 61 and the second telescopic rod 62. As shown in FIG. 10 and FIG. 5, both ends of the dumbbell body 10 are provided with a dumbbell piece mounting plate 5 for fixedly mounting the dumbbell piece. The dumbbell piece mounting plate 5 is provided with a telescopic rod exposing hole 51 for the first telescopic rod 61 or the second telescopic rod 62 to extend out from the dumbbell body 10. The telescopic rod exposing hole 51 is in a semicircular shape matching the shape of the first telescopic rod 61 or the second telescopic rod 62. The telescopic rod exposing hole 51 is fixedly provided with a limiting block 52 matching the shapes of the first sliding groove and the second sliding groove 624. The limiting block 52 is engaged in the first sliding groove or the second sliding groove 624 to form a circumferential limit to the first telescopic rod 61 and the second telescopic rod 62, so that the first telescopic rod 61 and the second telescopic rod 62 is able to move linearly to extend and retract in an axial direction thereof due to the formed circumferential limit (if the first telescopic rod 61 and the second telescopic rod 62 are not circumferentially limited, the first telescopic rod 61 and the second telescopic rod 62 will move spirally to extend and retract, which is undesirable).

The first telescopic rod 61 and the second telescopic rod 62 have a first end with an enlarged diameter (such as the first end 626 of the second telescopic rod 62 in FIG. 8) pointing to the outside of the dumbbell body 10. The first end is disposed in an enlarged diameter, so that it can be stopped by a hole end of an inner hole of the dumbbell body 10 when it is retracted into the inner hole of the dumbbell body 10. Specifically, in this embodiment, that is, the first end will be stopped by the hole end of a shaft hole of the gear shaft 46.

As in FIG. 11, in this embodiment, it is preferable that a connecting line of centers of the dovetail groove and the dovetail which are disposed 180° symmetrically on each end face of the dumbbell piece is in a plane where the first diametral plane or the second diametral plane 621 is located. Due to the disposing of the dovetail groove and dovetail tenon, the circumferential and axial movement of the dumbbell piece is limited by the cooperation of the dovetail groove and the dovetail tenon, the dumbbell pieces can only be disengaged from each other in the direction of the connecting line of the centers of the dovetail groove and the dovetail tenon. Therefore, the connecting line of centers of the dovetail groove and the dovetail tenon is disposed in the plane where the first diametral plane or the second diametral plane 621 is located, which can ensure that the first telescopic rod 61 and the second telescopic rod 62 are able to support the dumbbell piece most stably, so that the dumbbell piece will not fall off during the use of the dumbbell.

Referring to FIGS. 12-17, in this embodiment, the specific working principle of the flange driving member 2 and the planetary gear system 4 is as follows. The grip rod 1 is tubular in shape and has a center hole for the telescopic rod assembly 6 to extend through, an outer surface of the grip rod 1 has a concave-convex texture, to increase the friction of the user's grip. The grip rod 1 and the flange driving member 2 are fixedly assembled together. The flange driving member 2 is substantially funnel-shaped with the center hole 201, includes a housing portion 21, and also includes a screw hole 25 and a first pin 26 that are formed in an interior enclosed by the housing portion 21. The first pin 26 protrudes in the axial direction of the flange driving member 2. The housing portion 21 is in the shape of a shrunken cone and includes a small-diameter end toward the grip rod 1 and a large-diameter end toward the planetary gear system 4. The small-diameter end is fixedly assembled with the grip rod 1, and an outer diameter of the large-diameter end is substantially equal to that of the outer casing 41 of the planetary gear system 4, so that the large-diameter end is butted with the outer casing 41 of the planetary gear system 4 to substantially close the planetary gear and prevent dust from entering the planetary gear.

The planetary gear system 4 includes an outer casing 41, a ring gear 42 provided inside the outer casing 41, a load-bearing iron ring 43, a planetary wheel 44, a planetary carrier 45, and a gear shaft 46 serving as a sun wheel. The gear shaft 46 includes a shaft and a first gear 461 as an integral. The gear shaft 46 has a hollow shaft hole, and an inner wall of the shaft hole is provided with the concave helical groove 462, which is used to engage with an external thread of the first telescopic rod 61 or the second telescopic rod 62, so that when the gear shaft 46 is rotated, it drives the first telescopic rod 61 and the second telescopic rod 62 to extend or retract. The planetary carrier 45 is a revolving body with a substantially T-shaped cross-section, the planetary wheel 44 is rotatably sleeved on the planetary carrier 45, and the outer casing 41 is formed with a planetary carrier mounting hole 414 where the planetary carrier 45 is inserted and fixed, so that the planetary wheel 44 is mounted on the outer casing 41 through the planetary carrier 45. In this embodiment, five planetary wheels 44 are provided in a circular arrangement. In other embodiments, other suitable numbers of planetary wheels can be selected according to the load born by the planetary wheels. The ring gear 42 is engaged with the planetary wheel 44. The outer casing 41 has a center hole 412 for cooperating with the gear shaft 46. One end of the gear shaft 46 is inserted into the center hole 412, and the first gear 461 on the gear shaft 46 is engaged with the planetary wheel 44, so that the ring gear 42, the planetary wheel 44, the planetary carrier 45 and the first gear 461 form a planetary gear mechanism, the first gear 461 serves as a sun wheel, when the ring gear 42 is actively rotated, the first gear 461 is passively rotated, and the planetary gears form a speed-up transmission relationship.

The load-bearing iron ring 43 and the ring gear 42 are assembled and fixed, wherein an end face of the ring gear 42 is provided with a boss 421 protruding in its axial direction, and the load-bearing iron ring 43 is provided with an insertion hole 431 corresponding to the boss 421. The boss 421 is inserted into the insertion hole 431 to realize the cooperation of the load-bearing iron ring 43 and the ring gear 42. The load-bearing iron ring 43 is also fixedly assembled with the flange driving member 2, wherein the ring gear 42 and the load-bearing iron ring 43 are respectively provided with a first slot 423 and a second slot 433 at corresponding positions for the first pin 26 to be inserted and cooperated. The load-bearing iron ring 43 is provided with a through hole 432 whose position corresponds to the screw hole 25 of the flange driving member 2. When the flange driving member 2 and the planetary gear system 4 are engaged, the first pin 26 is aligned and inserted into the first slot 423 (the second slot 433) to complete the positioning, and then a screw is passed through the through hole 432 to be fixedly locked in the screw hole 25, so that the load-bearing iron ring 43, the ring gear 42 and the flange driving member 2 are connected into a whole. In order to facilitate the mounting and locking of the screws, the outer ring of the ring gear 42 is also opened with a groove 422 for giving way to the screws, and the outer casing 41 is formed with a screw insertion hole 415. Through the assembling relationship that the load-bearing iron ring 43, the ring gear 42 and the flange driving member 2 are connected into a whole, as the flange driving member 2 is rotated, the ring gear 42 can be rotated, and since the flange driving member 2 is fixedly assembled with the grip rod 1, when the grip rod 1 is rotated, the ring gear 42 can be rotated, and then through the driving of the planetary gear mechanism, the gear shaft 46 is rotated, then the gear shaft 46 drives the first telescopic rod 61 and the second telescopic rod 62 to extend or retract through the engagement of the helical groove 462 inside its shaft hole and the external thread on the first telescopic rod 61 or the second telescopic rod 62.

The outside of the outer casing 41 is screwed and fixedly connected with the dumbbell pieces 20 by a dumbbell piece mounting plate 5, so that by a gravity of the dumbbell pieces, the outer casing 41 is able to keep stationary when the grip rod 1 is rotated.

In this embodiment, when the grip rod 1 is rotated, the flange driving member 2 fixedly assembled with the grip rod 1 is rotated synchronously, and the flange driving member 2 drives the planetary gear system 4 to rotate the gear shaft 46. Through the driving of the planetary gear, it realizes that when the grip rod 1 is rotated at a smaller angle, then the gear shaft 46 will be rotated at a larger angle, thereby efficiently and accurately controlling the extension and retraction of the telescopic rod assembly 6.

In this embodiment, by providing two semicircular shaft-shaped first telescopic rods 61 and second telescopic rods 62, the extension range of the telescopic rod assembly is expanded under the limited length of the dumbbell body 10, and more dumbbell pieces can be mounted.

Although the present invention has been particularly shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the present invention without departing from the spirit and scope of the present invention as defined by the appended claims, which fall within the protection scope of the present invention. 

What is claimed is:
 1. An adjustable dumbbell, comprising: a dumbbell body, and dumbbell pieces cumulatively attached to both ends of the dumbbell body, wherein: the dumbbell body comprises a grip rod, mounting portions disposed at both ends of the grip rod for connecting the dumbbell pieces, a first telescopic rod extending inside the dumbbell body, and a second telescopic rod extending inside the dumbbell body, the first telescopic rod and the second telescopic rod are driven by the dumbbell body to extend from or retract into the dumbbell body away from each other to hang the dumbbell pieces so as to adjust a number of dumbbell pieces at the both ends of the dumbbell body, the first telescopic rod and the second telescopic rod are substantially in a shape of a semicircular shaft, the first telescopic rod comprises a first semicircular plane and a first diametral plane to define the shape of the semicircular shaft, the first diametral plane is provided with a first sliding groove opened in a length direction of the first telescopic rod, the second telescopic rod comprises a second semicircular plane and a second diametral plane to define the shape of the semicircular shaft, the second diametral plane is provided with a second sliding groove opened in a length direction of the second telescopic rod, a plane where the first diametral plane is located and a plane where the second diametral plane is located face each other so that the first telescopic rod and the second telescopic rod are staggeredly arranged in the dumbbell body, the dumbbell body is fixedly provided with a first limiting block and a second limiting block respectively matching the first sliding groove and the second sliding groove, and the first limiting block and the second limiting block are respectively slidably engaged in the first sliding groove and the second sliding groove, thereby restricting a circumferential rotation of the first telescopic rod and the second telescopic rod.
 2. The adjustable dumbbell according to claim 1, wherein: a first end of the both ends of the dumbbell body has a first exposing hole for exposing the first telescopic rod, a second end of the both ends of the dumbbell body has a second exposing hole for exposing the second telescopic rod, the first exposing hole and the second exposing hole are semicircular shaped, respectively matching the shape of the first telescopic rod and the shape of the second telescopic rod, and the first limiting block and the second limiting block are respectively fixedly disposed in the first exposing hole and the second exposing hole.
 3. The adjustable dumbbell according to claim 1, wherein: the first telescopic rod further comprises a first sliding block disposed on the first diametral plane, the second telescopic rod further comprises a second sliding block disposed on the second diametral plane, and the first sliding block is slidably connected in the second sliding groove and the second sliding block is slidably connected in the first sliding groove so that the first telescopic rod and the second telescopic rod are slidably connected.
 4. The adjustable dumbbell according to claim 3, wherein: the first sliding groove has a first end, the second sliding groove has a second end, and when the first telescopic rod and the second telescopic rod are extended away from each other, the first sliding block and the second sliding block are configured to abut the second end and the first end, respectively, thereby inhibiting the first telescopic rod and the second telescopic rod from disengaging from each other.
 5. The adjustable dumbbell according to claim 1, wherein: one end of the first telescopic rod and one end of the second telescopic rod, pointing to an outside of the dumbbell body, each has a radially extending hooking portion, and when the first telescopic rod and the second telescopic rod are retracted, the radially extending hooking portion is configured to be hooked on end faces of the both ends of the dumbbell body, thereby inhibiting the first telescopic rod and the second telescopic rod from retracting into the dumbbell body.
 6. The adjustable dumbbell according to claim 5, wherein the radially extending hooking portion complements the one end of the first telescopic rod and the one end of the second telescopic rod pointing to the outside of the dumbbell body to define a circular shape.
 7. The adjustable dumbbell according to claim 1, wherein the first telescopic rod and the second telescopic rod are connected to the dumbbell body by a screw pair with opposite rotation directions so that, by rotating the dumbbell body, the first telescopic rod and the second telescopic rod are driven to extend from or retract into the dumbbell body away from each other.
 8. The adjustable dumbbell according to claim 7, wherein: the first semicircular plane and the second semicircular plane are protrudingly provided with a first thread and a second thread with opposite rotation directions, respectively, and the dumbbell body is provided with a first helical groove and a second helical groove that are matingly connected with the first thread and the second thread, respectively.
 9. The adjustable dumbbell according to claim 1, wherein an end of the first telescopic rod and an end of the second telescopic rod pointing to an outside of the dumbbell body has a diameter enlarged portion with an enlarged diameter.
 10. The adjustable dumbbell according to claim 1, wherein: end faces of both sides of the dumbbell pieces are provided with 180° symmetrically disposed clamping blocks and clamping grooves, adjacent dumbbell pieces of the dumbbell pieces are cumulatively stacked at the both ends of the dumbbell body through snap fitting of the clamping blocks and the clamping grooves, and a connecting line of centers of each group of the 180° symmetrically disposed clamping blocks and clamping grooves is in a plane where the first diametral plane or the second diametral plane is located. 